That sound to me as bad PCB design and/or power supply. But sill could be bad LCD driver.
If long delays make artifact disappear, then capacitive coupling between LCD signals and power lines can cause that.
You can try test that. Add pull down resistor 1K to LCD Enable pin, and create easy way to disconnect LCD and resistor from PIC, as close as possible to LCD.
Code:
pause 500
                        
lcdout $FE,$28
lcdout $FE,$17
lcdout $FE,$06
lcdout $FE,$08
lcdout $FE,$01
lcdout $FE,$02
lcdout $FE,$0C

lcdout $FE,$80,"BU BiR DENEMEDiR"
LCDOUT $FE,$C0,"  iKiNCi SATIR  "
PAUSE 10000' Disconnect only LCD enable pin before pause timeout
Main:
lcdout $FE,$80,"BU BiR DENEMEDiR"
LCDOUT $FE,$C0,"  iKiNCi SATIR  "
GOTO Main
Display shouldn't update any more. If you see dots then 99% problem is with PCB layout, and decoupling.
If there is no dots on LCD then problem is with LCD.